Novak Djokovic of Serbia celebrates defeating Kei Nishikori of Japan during their men's quarterfinal match at the Wimbledon Tennis Championships in Lo

Kevin Anderson of South Africa celebrates winning his men's quarterfinals match against Switzerland's Roger Federer, at the Wimbledon Tennis Champions

John Isner of the United States celebrates winning the second set of his men's quarterfinals match against Canada's Milos Raonic, at the Wimbledon Ten

LONDON (AP) — After so much speculation about a possible Wimbledon final between Roger Federer and Rafael Nadal, 10 years after their last, the tennis world instead will get a semifinal featuring another outstanding rivalry: Nadal vs. Novak Djokovic.

Friday's showdown will be their 52nd meeting overall — the most for any pair of men and 14 more installments than Federer vs. Nadal — and first at the All England Club since 2011.

That was also the last time Nadal made it past the fourth round at the grass-court major; Djokovic, who holds a 26-25 head-to-head lead, beat him in that year's final.

"We always played in important stages, important places," said Nadal, who had a far rougher go of things in the quarterfinals than Djokovic, needing more than 4½ hours to edge Juan Martin del Potro in a five-set thriller. "Friday is another important match against an opponent that is one of the most difficult ones that you can face. He's playing well. Only way to try to win it is (to) play very well."

The first semifinal at Centre Court, between No. 8 seed Kevin Anderson of South Africa and No. 9 John Isner of the U.S., features two powerful servers with similar games who have a lot less star power and considerably fewer Grand Slam trophies, to say the least: The Nadal-Djokovic combined count is 29, including five at Wimbledon.

There are zero major titles so far for either Isner, 33, or Anderson, 32, who shockingly ended Federer's bid for a ninth championship at Wimbledon by erasing a match point and beating him 13-11 in the fifth set of their quarterfinal Wednesday.

At least Anderson can boast of one runner-up finish, and it was recent, against Nadal at last year's U.S. Open.

"I'm trying to get to where he's already been," said Isner, who has won all 95 of his service games this fortnight, thanks in part to a tournament-leading 161 aces. "He wants to get back there, wants another crack at a championship."

Isner, who leads Anderson 8-3 in past meetings, is making his debut in the final four of a Grand Slam tournament in his 41st appearance at one. He'd only once before reached the quarterfinals at any major, back in 2011, and never had been past the third round at the All England Club.

Add in Nadal, 32, and Djokovic, 31, and it's the first time in the half-century of professional tennis that all four male semifinalists at any Slam are in their 30s.

That's a reflection of a trend that's been present in the men's game for quite some time.

With the increasingly physical nature of rallies, the advances in training and nutrition that help extend careers, and the dominance of a certain trio of all-time talents — Federer has 20 Grand Slam titles, Nadal 17, Djokovic 12 — it's been hard for any youngsters to elbow their way to the top.

Djokovic seems to once again be claiming his spot among the very elite.

Since winning the 2016 French Open to complete a career Grand Slam and collect a fourth consecutive major trophy, he hasn't added to his total. He has one Slam final appearance in that span.

A significant part of the problem was a painful right elbow that forced him off the tour for the second half of 2017 after he stopped playing during his Wimbledon quarterfinal. After more than a year of trouble, Djokovic finally had surgery in February, then took a while to find his groove.

"If I have to compare the game that I've played, the level of tennis that I've had (all of) those years and today, I think it's pretty close. ... I know, as everything in life, we are evolving. I'm a different person, different player today," Djokovic said.

"I like the level of tennis that I'm playing on right now. I really do. I think with the performances I've had, I deserve to be in the semifinals," he continued. "I don't want to stop here. I hope I can get a chance to fight for a trophy."